Tucson is test site for new IBM solar technology

﻿IBM says it has reached an overall system efficiency of 30 percent sunlight-to-power conversion using its concentrating photovoltaic system, above, which is being tested in Tucson and Boulder, Colo.

The University of Arizona Science and Technology Park is home to several massive solar-energy projects as part of its Solar Zone demonstration project.

But one recent addition there isn’t part of the Solar Zone — it’s a small test array tucked away behind IBM Corp.’s building in the tech park.

IBM’s research arm recently announced that it has developed new technology for so-called concentrating photovoltaics, with test systems installed recently at IBM sites in Tucson and in Boulder, Colo.

IBM’s research chops in computing are well-known, but solar?

It’s not such a big leap for Big Blue, says Tim Dalton, manager of IBM’s Nano-Science and Technology Partnership Program, noting that the company has long designed and built its own computer chips and systems.

“The technology to do photovoltaics, be it PV chips or systems, is not that much different,” said Dalton, an IBM “master inventor” based in Yorktown Heights, N.Y.

Concentrating photovoltaics involve the use of lenses or mirrors to gather sunlight and concentrate it on PV cells. The idea is to focus the concentrated sunlight on super-high-efficiency cells, to achieve maximum power output with minimal PV material.

It’s not an entirely new idea; in fact, the UA Tech Park’s Solar Zone includes a big example in a large concentrating PV array made by California-based Amonix, which pioneered the technology more than 20 years ago but last year shut down a new plant amid a financial restructuring.

The UA Tech park also is the site of a concentrating PV demonstration array invented by UA astronomy professor Roger Angel that uses mirrors to focus sunlight on a ball-shaped lens surrounded by high-efficiency PV cells.

Using mainly off-the-shelf components — including so-called multijunction PV cells and Fresnel lenses — IBM says the concentrating PV system it has developed can convert sunlight to DC electricity at a rate of 30 percent, compared with about 20 percent for typical silicon PV cells.

(While some PV cell makers, including Boeing’s Spectrolab, have cited conversion efficiencies of more than 40 percent at the cell level, claimed system-level efficiencies peak at about 30 percent.)

IBM’s PV research grew out of a wide-ranging technology brainstorming event called Innovation Jam in 2006. During the three-day, global event, participants asked what IBM could do to boost renewable energy, Dalton said.

Focusing on concentrating PV, IBM built and refined systems using multifunction cells from Spectrolab and others, Fresnel lenses and a lightweight dual-axis tracking system to keep the cells pointed toward the sun.

IBM researchers then tackled one of the biggest problems with concentrating PV — excessive heat that can degrade system efficiency.

With initial prototype systems installed in New York and in Saudi Arabia, IBM developed a proprietary passive-cooling system based on its work to keep supercomputer components from overheating, Dalton said.

While some concentrating PV designs feature cooling fans or even liquid radiator systems for cooling, Dalton said IBM’s solution involves the finned assemblies commonly used as heat sinks in computers and other electronics.

“It’s a simple fin assembly, but it’s not just the fins: You have to think about the entire packaging,” he said.

Together with cells made for relatively high heat tolerance, the system can keep delivering power efficiently at temperatures up to about 90 to 100 degrees Celsius (194 to 212 degrees Fahrenheit), Dalton said.

The grid-tied test rigs were installed in Tucson in April and in Boulder in March to test their efficiency in temperature extremes, and they’re being monitored to gather test data.

While Dalton’s excited about the technology, he notes IBM doesn’t plan on opening a PV plant anytime soon. IBM — the perennial world leader in patenting — has about 25 patent applications for concentrating PV inventions pending, he said, and plans to make the technology available for licensing.

Dalton said the IBM design wouldn’t be appropriate for every application but could find a niche where compact, high-energy solar arrays are needed.

It’s also a tough market in general for advanced solar technologies — just ask Amonix. A flood of cheap silicon-based solar panels from China has led to U.S. tariffs on Chinese products, but many companies pushing thin-film semiconductor alternatives are still struggling.

In its current state of development, the IBM system’s main competitive advantage is in places like Tucson and Boulder, which have mostly sunny skies and high solar radiation, or insolation.

But IBM is working to optimize the system for cloudier climes, Dalton said.